Slurry feed device



May 2, 1961 R. B. TlLNEY SLURRY FEED DEVICE Filed 0G17. l2, 1956 United States Patent() SLURRY FEED DEVICE Ralph B. Tilney, Clayton, Mo., assigner to Alco Valve Company, St. Louis, Mo., a corporation of Missouri Filed Oct. 12, 1956, Ser. No. 615,609

4 Claims. (Cl. 302-14) tions.

The slurry feed device of this invention is designed to provide means for transporting a slurry comprising liquid and fine particles of solid matter, such as alumina to dispense it through a small tube for ultimate usage. Particular advantage is found in the eld of ultrasonic drilling where the slurry includes ne abrasive particles of alumina. In such applications, the slurry is dispensed througha tube forming part of the dental drilling equipment. The physical character of the slurry actually is a a form of mist or a froth when discharged from the end of the tube and the drill into the patients mouth, and may be considered to be a mixture of air with droplets of the slurry liquid.

In the past, the provision of a device for feeding liquid suspensions of alumina in dental drilling applications, in particular, have met with difliculties due to caking of the slurry within the small diameter dispensing tubes employed. In the instant invention, this is obviated and there is means provided for maintaining aV sup- Patented May 2, 1.961

mixture through a dispensing tube in order that the slurry maybe dispensed in the form of a mistior a froth in conjunction with a dental drilling tool into ,a dental patients mouth in the drilling operations. t

Still another object of this invention is to provide a slurry feed `device comprising a reservoir and an air tube slurry mixing and driving and agitating or circulating means which yis rugged in construction and simple in operation Vin which no ,moving parts are required.

Further objects of this invention will appear in the detailed description which follows and will be further apparent to those skilled Vin the art.

Y For the purpose of illustration of this invention, there lCe is shown in the accompanying drawings a preferred ernply of the liquid slurry in constant circulation which provides for very eilicient mixing.

The improved slurry feed device of this invention has been made possible by providing a liquid reservoir of the slurry into which a source of air pressure is directed to a tube. The air tube which is directed beneath the surface of the slurry, is provided with a venturi construction having aspirator passages for the entry of the slurry.

The tube is extended with an end opening being directed into the liquid below the surface and a takeoff tube being provided through which the air and slurry mixture is dispensed ultimately to the drilling equipment. The apparatus is simple in construction and operation Vand can be very conveniently installed in a dentists oice and also employed in other applications, where desired.

Accordingly, it is a primary object of this invention ,to provide an air feed device for transporting a slurryand air mixture through a tube.

It is a further object of this invention to provide a slurry feed device in which a slurry of solid discrete particles and liquid are mixed with air as a transporting medium in a small tube and to be dispensed in the form of a mist or froth.

Yet a further object of this invention is to provide a s-lurry feed device in which a reservo-ir of a slurry of liquid and discrete particles is agitated by an air source and in which the slurry is introduced yfrom the reservoir into an air line and transported through a discharge tube.

Yet another object of this invention is to provide a slurry feed device for dispensing a slurry of liquid and discrete solid particles through an air-tube vdrivingmeans in which the tube is provided with a venturi passage .and aspirating means associated therewith to suck in slurry from the reservoir and then drive an air vand slurry bodiment of this invention, as welll asV a modification which permits adjustment of the mixing opening adjacent the '-venturi passage. Itis to be understood that these drawings are forthe purpose of illustration only and that the invention is not limited thereto. In the drawings:

Figure 1 is a view in side elevation taken through a vertical sect-ion of a reservoir and showing the slurry feed device;

Figure 2 is a top plan View of the slurry feed device and reservoir of Figure 1;

Figure 3 is an enlarged view in section taken on the line 3 3 of Figure 2 showing the venturi passage of the slurry feed device and the mixing opening as Well as the slurryrfeed device discharge tube;

Figure 4.is anenlarged View in section taken on the line 4-4 of Figure 3;

Figure 5 is an enlarged view in section taken on the line 5 5 of Figure 1 vshowingthe construction of the venturi opening and slurry mixing opening; and

Figure 6 is a view vin section taken through the axis of a modied form of the Vslurry feed mixing device showing the venturi passage and means for varying the size of the mixing opening adjacent the venturi.

In Figures 1 and 2, the slurry feed device is generallyV indicated by the numeral 10. It is shown disposed within a reservoir 11 lled witha liquid slurry to the, level indicated by the numeral Y12.

The slurry feed device 10 is comprised Vof an `inlet tube 13 for the introduction of air under pressure, a mixing body 14, a slurry discharge tube 15 and an agitating or circulating tube 16.

The mixingV body 14 lis shown in more specific detail in Figures 3, 4, and 5. It is comprised of a solid block of metal or other suitable material of construction in which the end of thevair inlet tube 13 is disposed in open communication with a venturi passage -generally indicated by the numeral 21. The venturi passage has a rear opening 2-2 against which the end of the inlet tube visv ward portion of themixing block 14, and shown inV the form of ,an',. is the discharge 4tube l5 which is of smaller diameterfthanthe .circulatingtube 1 6. .'Ilhis tube may be conveniently connected to a rubber Vhose or the like for Athe connection of the'device to ya dental drill. It will be noted that the discharge tube 15 ,'is

located in the side of -the agitating tube midway'` the L top and the bottom fwhich gives advantageous -esxfiltsi and the distribution of slurry through this Yt'ube.

.In themodifcation of4 Figure 6 is shownfmeans for varying the effective size of the mixing passages adjacent the constriction in the' venturi opening of the slurry feed mixing device. In this modiication, the mixing body is generally indicated by the reference numeral 30 and at its forward end, the circulating tube 16 is disposed in similar manner to that previously described. At the rear of the mixing body is a hollowed out portion 31 having internal threads 32 and which is in communica tion with mixing passages 25 and 26. A venturi nipple is generally indicated by the numeral 33 and has a threaded exterior 34 to cooperate with the internal threads 32 of the mixing body. A hexagonal flange 3S is provided for use in adjustment of the nipple into the body of the mixing block 30.

The venturi nipple has an interior opening 36 which converges inwardly to form a constricted venturi opening 37 disposed within the center of the end of the agitating tube 16. The interior opening 36 of the venturi nipple may receive the end of the inlet air tube 13 and packing 39 is provided so that a sliding t may be realized for relative movement between the tube and the nipple, where desired.

Through this construction, the venturi nipple may be screwed into or out of the block 30. In such manner, the spacing between the exterior of the end of the venturi opening 37 and the interior of the tube 16 will be either decreased or increased to vary the eiective size of the mixing passage and meter the proportion of slurry to air.

Use

The slurry feed device 10, as shown in Figure 1, may be very advantageously used in dental drilling operations, for example, in which the solid particles are abrasive alumina. Such solid particles may be in the range of a 325 mesh screen to a 200 mesh screen and the' slurry may be by weight of the alumina to water.

In the usage of the device, air at pressure of 10 lbs. per square inch, for example, may be introduced into the inlet air tube 13. This air, when it passes through the venturi passage 21 in the mixing block 14, will increase greatly in velocity and decrease in pressure due to the constriction 23. This produces an aspirating or suction effect through the mixing passages 2S and 26 and slurry is drawn into these passages and mixed with the air. The discharged mixture comprises air and slurry which is fed into the circulating tube 16 and is drawn oi through the discharge tube for end usage. This end usage may be through a tube associated with the dental drilling equipment and the slurry and air will be discharged in the form of a mist or froth in a desired manner, and against a dental patients tooth for the drilling operation. It is, of course, to be understood that this apparatus is not limited to such usage and may be employed in other applications.

The circulating tube 16 provides for the discharge of the air and recirculation of the slurry and air mixture within the reservoir to provide for gentle agitation and circulation of the slurry to prevent sedimentation. It will be noted that this discharge is generally in the region of the aspirator openings which provide for ecient circulation of the slurry in this important area.

In the modication of Figure 6, the usage is the same as that described above. However, it will be noted that the venturi nipple generally indicated by the reference numeral 33 can be adjusted with respect to the mixing body 30 by screwing it into the body or away from it to reduce or increase the eiective area of the mixing passages 25 and 26' into the interior of the circulating tube 16. Thus, the proportional mixture of slurry wit respect to air can be easily varied in this application.

The slurry feed device of this invention is found to be very desirable in dispensing through discharge tubes in the order of l inch in diameter where caking has been previously a problem. Such sizes are not limiting, however, nor is the device limited to use in dental drilling applications where, however, the invention does find particular advantage. Also, throughout this application, the mixing fluid has been called a slurry, but it is to be understood that other physical forms of liquid or other fluids could be equally well employed.

Various changes and modifications may be made within the slurry feed device of this invention, as will be apparent to those skilled in the art. Such changes and modifications are within the scope and teaching of the invention, as defined by the claims appended hereto.

What is claimed is:

l. A device for feeding and dispensing a slurry from a slurry reservoir which comprises means for conducting air under pressure into a mixing body, said body being provided with aspirating means for drawing slurry into the body and mixing it with air, and discharge means for dispensing the mixed air and slurry from the body, said discharge means including a passage for dispensing the mixed air and slurry under pressure from the reservoir, and a recirculating passage adapted to recirculate mixed air and slurry into the reservoir adjacent said aspirating means beneath the slurry level for agitation and circulation of the slurry.

2. A device for feeding and dispensing a slurry from a slurry reservoir which comprises means for conducting air under pressure into a mixing body, said body being provided with aspirating means for drawing slurry into the body and mixing it with air, said aspirating means comprising a venturi passage having a converging inlet and an outlet of increased diameter separated by a throat. and passage means connecting the throat with the exterior of the body for the introduction of slurry from the reservoir into the venturi passage, and discharge means for dispensing the mixed air and slurry from the body, said discharge means including a recirculating passage for recirculating mixed air and slurry through an outlet opening into the reservoir adjacent said aspirating means at substantially the same level as the aspirating means and a conduit for dispensing the mixed air and slurry under pressure outside the reservoir.

3. A device for feeding and dispensing a slurry from a slurry reservoir which comprises means for conducting air under pressure into a mixing body, said body being provided with aspirating means for drawing slurry into the body and mixing it with air, said aspirating means comprising aventuri passage having a converging inlet and an outlet of increased diameter separated by a throat, and passage means connecting the throat with the exterior 1 of the body for the introduction of slurry from the reservoir into the venturi passage, and discharge means for dispensing the mixed air and slurry from the body, said discharge means including a recirculating passage for recirculating mixed air and slurry through an outlet opening into the reservoir adjacent said aspirating means at substantially the same level as the aspirating means and a conduit for dispensing the mixed air and slurry under pressure outside the reservoir, said dispensing conduit having an inlet connected intermediate the outlet of the body and the outlet of the recirculating passage.

4. A device for feeding and dispensing'a slurry from a slurry reservoir which comprises means for conducting air under pressure into a mixing body, said body being provided with aspirating means for drawing slurry into the body and mixing it with air, said aspirating means comprising a venturi passage having a converging inlet and an outlet of increased diameter separated by a throat, and passage means connecting the throat with the exterior of the body for the introduction of slurry from the reservoir into the venturi passage, and discharge means for dispensing the mixed air and slurry from the body, said References Cited in the iile of this patent UNITED STATES PATENTS Miller Jan. 23, 1900 Beth Mar. 2, 1926 Earman Sept. 16, 1930 Hueber Feb. 16, 1932 Aherne Aug. 15, 1933 

